Circuit breaker



Sept. 24, 19%.;

J.,M.CUMMING ETAL 2,408,199

CIRCUIT BREAKER Filed Sept. 15, 1941 2 Sheets-Sheet 1 WETNESSES:INVENTORS JamesM Cummin 2 R/ClyG/d C (unm'lgzzam Patented Sept. 24, 1946UNITED STATES PATENT OFFICE CIRCUIT BREAKER James M. Cumming, TurtleCreek, and Richard C. Cunningham, East Mclieesport, Pa., assignors toWestinghouse Electric Corporation, East Pittsburgh, Pin, a corporationof Pennsylvania Application September 13, 1941, Serial No. 410,686

17 Claims. 1

The invention relates to circuit breakers, and more particularly to highspeed circuit breaker operating mechanisms of the pneumatic type.

High speed operation of circuit breakers is becoming increasinglyimportant, and circuit breakers are now desired embodying operatingmechanisms which are capable of quickly re- Versing the switchingmovement of the contacts in order to provide high speed opening of thecontacts, and quick automatic reclosing of the contacts immediatelyafter interruption of a short circuit. Automatic reclosing time can bematerially reduced by quickly reversing the opening movement of thebreaker to reclose the same immediately after interruption of thecircuit, particularly if the reclosing movement is initiated before thebreaker reaches full open position. It is also important that thebreaker shall be opened quickly without substantial retardation inresponse to an overload. The movement of the contacts must be reversedquickly to opening movement without substantial retardation when thebreaker is being closed or automatically reclosed against a fault, eventhough the closing air pressure is still being admitted to the operatingcylinder.

An object of the invention is the provision of a circuit breakerembodying an operating mechanism operable by fluid pressure to close thebreaker and having an improved construction which will permit quickreversal of operation of the breaker in either direction of movement.

Another object of the invention is the provision of a circuit breakerembodying an operating mechanism pneumatically operated to close orautomatically reclose the breaker, and having means for causing quickand substantially unretarded opening of the breaker in response topredetermined abnormal conditions in the circuit even if the abnormalcondition occurs at the instant the circuit is closed.

Another object of the invention is the provision of a circuit breakeroperating mechanism which. is operated by fluid pressure to close orautomatically reclose the breaker, and means for causing quick collapseof the closing fluid pressure in the operating cylinder upon theoccurrence of predetermined abnormal conditions in the circuit to causequick and substantially unretarded opening of the breaker in response tosaid condition even if the main inlet valve of the mechanism is open atthe time.

Another object of the invention is the provision of a circuit breakeroperating mechanism operated by fluid pressure to close or toautomatically reclose the breaker and having an adequate fluid pressureexhausting means controlled by the circuit breaker tripping means toprovide for quick and substantially unretarded opening of the breakerand produce the effect of trip free action without disconnecting theoperating piston from the breaker.

Another object of the invention is the provision of a circuit breakeroperating mechanism operated by compressed air to close or automaticallyreclose the breaker and having an improved air pressure exhaustingmeans, for the operating cylinder, controlled by the circuit breakertripping means so that a tripping impulse will always take precedenceover a closing impulse thus providing the effect of trip free actionwithout disconnecting the main circuit breaker operating piston from thebreaker.

Another object of the invention is the provision of a circuit breakeroperating mechanism which is pneumatically operated to close orautomatically reclose the breaker and provided with a main exhaust valveof the piston type which is opened by air pressure under the control ofa light pilot valve operated by the armature of the circuit breakertripping means, whereby the exhaust valve is caused to open by airpressure in the operating cylinder at the same time the circuit breakeris unlatched or tripped, Without adding an appreciable load on thecircuit breaker tripping coil.

Another object of the invention is the provision of a circuit breakeroperating mechanism operable to close or quickly reclose the breaker byfluid pressure and having an exhaust passage larger than the main inletpassage and an exhaust valve controlled by the circuit breaker trippingmeans to provide trip free action, the exhaust passage being located inthe operating cylinder so as to be closed by the main operating pistonbefore it reaches the position at which fluid pressure is admitted forquick reclosure thus preventing exhausting of the reclosing fluidpressure and at the same time allowing a sufiicient time interval forthe mechanical closing of the exhaust valve on a quick reclosingoperation.

Another object of the invention is the provision of an improved circuitbreaker operating mechanism of the pneumatic type, which is simple,reliable in operation and inexpensive to manufacture.

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The inventionitself, however, both as to structure and operation together withadditional objects and advantages thereof will be best understood fromthe following detailed description of several embodiments thereof whenread in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a circuit breaker operatingmechanism embodying the features of the invention, the mechanism beingshown in the closed position by the full lines;

Fig. 2 is a fragmentary sectional view, taken substantially along theline IlI--II of Fig. 1, show-- ing the exhaust valve of the mechanism,which cannot be seen in the section of Fig. 1;

Fig. 3 is a wiring diagram of the circuits for controlling opening andclosing of the circuit breaker, the operating mechanism and circuitbreaker being illustrated schematically in this figure; and

Fig. 4 is a fragmentary sectional View similar to Fig. 2 butillustrating a modified construction of the exhaust valve.

Referring to the drawings, the circuit breaker 1 shown schematically inFig. 3, may be of any conventional construction either of the oil break,air break or gas blast type. The circuit breaker, as shown, comprisesstationary contact means 9 and cooperating movable contact means H forcontrolling a main circuit represented diagrammatically by a single line|3. Although illustrated as a single pole circuit breaker, it will, ofcourse, be understood that the breaker may be a multipole circuitbreaker having a set of contact means 9| for each pole thereof with themovable contact means mechanically connected for simultaneous operationin the usual manner. The circuit breaker is biased to open circuitposition by means of an accelerating spring shown schematically at l5,and the breaker is mechanically connected to the operating mechanismindicated generally at l1 by suitable connecting means. The connectingmeans is represented schematically as comprising a lever 9 pivoted at 2|on a fixed support, one end of the lever being pivotally connected tothe breaker lift rod 23 and the other end being pivotally connected tothe breaker operating rod 25 which is, in turn, mechanically connectedto the operating mechanism l1.

Referring now to Fig. 1, the operating mechanism comprises a maincasting 21 which is formed to provide a cylinder 29 closed at the upperend by an integral part of the casting. A closure member 3| is securedto the lower end of the cylinder 29 to close this end of the cylinder,and this closure member has a relatively large port 33 therein which isopen to the atmosphere. An operating or latching lever 35 is pivotallymounted at one end on the casting 21. The operating lever consists oftwo spaced parallel levers 31 (only one being visible in Fig. l) whichare pivotally connected at one end by means of a pivot pin 39 to theupper end of a pair of parallel links 4| (only one appearing in Fig. 1)which are in turn pivotally mounted on an car 43 of the main casting 21by means of a pivot pin 44. The opposite end of the levers 31 comprisingthe operating lever 35 are connected by a cross member and carry a shortshaft 45 therebetween, on which is rotatably mounted a roller 41disposed between the parallel levers 31. The breaker operating rod 25 ispivotally connected by a pivot pin 49 to an intermediate point of theoperating lever 35, the pivot pin 49 extending transversely through theparallel levers 31 and engaging an opening in the lower end of the rod25 which is disposed between the parallel levers. The breaker operatinglever 35 is adapted to be held in the closed position, shown in Fig. 1,to hold the breaker closed, by means of a high speed latching mechanismcomprising a main latch 5| which is pivoted on the main casting 21 bymeans of a pivot pin 53. The latch 5| is adapted to extend between theparallel levers 31 and its latch end is adapted to engage and restrainthe roller 41 carried by the free end of the breaker operating lever 35.The latch 5| is biased to latching position against a stop 55 by meansof a spring pressed plunger 51 which engages a projection 59 of thelatch. The plunger 51 is slidably mounted in an opening in a portion ofthe main casting 21 and is biased inwardly against the projection 59 ofthe latch 5| by means of a compression spring 5| surrounding the plunger51 and disposed between the head thereof and a plate 63 secured to thecasting 21. An adjustable nut 65 is threaded on the outer end of thespring pressed plunger 51 and this nut serves to limit inward movementor the plunger.

The construction of the latch face of the main latch 5| is such thatthis latch alone will not serve by itself to hold the breaker operatinglever 35 in closed position unless the main latch is itself held inlatching position. An auxiliary latch 61 is provided for normallyengaging and holding the main latch 5| in latching position. Theauxiliary latch 61 is pivoted on the casting 21 by means of a pivot pin69 and has a latch projection 1| which is adapted to engage under a tailprojection 13 of the main latch 5| in the latching position of thelatching means. The auxiliary latch 61 is biased to latching position,as shown in Fig. 1, by a compression spring 15 which is seated in arecess in the casting 21 and engages an integral projection of theauxiliary latch. The auxiliary latch 61 is also provided with aprojection 11 which extends directly over the upper end of the tripplunger 19 of an electromagnetic trip device 8|. The trip device 8|comprises in addition to the trip plunger 19, an E-shaped core 83 ofmagnetic material, an energizing winding 85 which is mounted on thecenter leg of the E.- shaped core, and a movable armature E1 cooperatingwith the core 83. The trip plunger 19 is secured to the center portionof the armature 81 and slidably extends upwardly through a guide openingin the center portion of the core 83 and through an opening in thehorizontal portion of the main casting 21. The armature 81 is biaseddownwardly to unattracted position, as shown in Fig. 1, by a compressionspring 89 which encircles the upper portion of the plunger 19 and isdisposed between a collar 9| secured to the plunger and a bushing 93which is threaded in the upper end of the opening of the casting throughwhich the plunger extends. When the trip device 8| is energized, thearmature 81 thereof is moved upwardly against the core 83 causing upwardmovement of the trip plunger 19. This upward movement of the tripplunger causes the auxiliary latch 1| to be rotated counterclockwise anddisengage the projection 13 of the main latch 5|, whereupon theaccelerating spring l5 of the circuit breaker moves the breaker to opencircuit position, the operating lever 35 being rotated counterclockwiseabout its pivoted end by the opening movement of the breaker. During theinitial opening movement of the operating lever 35, the roller 41 forcesthe main latch 5| in a counterclockwise direction as it clears thelatch. In order to prevent the auxiliary latch from being returned tolatching position until the breaker operating lever 35 is returned toclosed position there is provided a U-shaped holding lever 95 the legsof which are pivotally mounted on the ends of the pivot pin 69 onopposite sides of the auxiliary latch til. The holding lever 95 isbiased in a counterclockwise direction by the compression spring 91which is seated in a recess in the casting 21 and engages a projection$9 of the holding lever. A cross member ml of the holding lever 95 isdisposed directly beneath the end of the operating lever 35 so as to beheld in inoperative position when the operating lever 35 is in closedposition. However, when the operating lever is released and moves towardopen position, the holding lever 95 is rotated in a counterclockwisedirection and a lateral extension I09: of the portion 99 of the holdinglever engages and holds the auxiliary latch 61 in unlatched positionuntil the breaker operating lever 35 is returned to closed position andits roller has become reengaged by the latch face of the main latch 5i.For this purpose the biasing spring 91 of the holding lever is ofgreater strength than the auxiliary latch biasing spring I5.

An operating piston ")3 having piston rings N35 is movable within theoperating cylinder 29 and this piston has a piston rod Ill! whichslidably extends in a fluid tight manner through an opening providedtherefor in the top wall of the cylinder 29. The upper end of the pistonrod Iiil has a connecting element H39 threadedly connected thereto,which is pivotally connected to the pivot pin 49 carried by theoperating or latching lever 35. Thus the operating piston I93 ismechanically connected directly to the circuit breaker operating rod 25.The purpose of the lever 35 is to provide a mechanical advantage for thelatching means to reduce the latch load, otherwise the lever 35 could beomitted and the latch arranged to latch directly on the operating rod.The operating piston IE3 is adapted to be moved downwardly in thecylinder 29 to close or automatically reclose the circuit breaker, bycompressed air from an auxiliary air reservoir or tank HI, thecompressed air being admitted to the upper end of the operating cylinder29 through an inlet passage controlled by a main inlet valve indicatedgenerally at I 3. The opening operation of the main inlet valve is, inturn, controlled by a pilot valve H5 operated by an electromagnet ill.

A skirt on the lower end of the operating piston I03 cooperates with anannular recess I 84 formed by the closure plate 3: to provide a dash potaction to help in, stopping the piston at the end of its downward orclosing stroke.

The main inlet valve [l3 comprises av valve housing I59 which is securedto the side of the main cylinder casting 27 by a plurality of bolts (notshown), and this valve housing is provided with inlet passages I2 l andthe former communicating with the auxiliary air reservoir Hi and thelatter communicating with an inlet port I25 in the upper end of the maincylinder 25. A main valve element 52! disposed in the valve housing hasa stem I25 slidably mounted in guide sleeve '53.! which is carried by abushing I33. The bushing I33 is threaded in an opening in the valvehousing between the passages 12! and 823, and this bushing serves as avalve seat fer the valve element M27. The guide sleeve I35 is connectedto the bushing :33 by a plurality of. spider legs which permit thecompressed air to flow through the passages iZI and when the valve isopen. The valve element 522: is biased to closed position, as shown inFig. 1, by means of a helical compression spring I 351- which surroundsthe guide sleeve I 3|. The lower end of the valve biasing spring I35bears against the spider legs of the bushing I33 and the upper end ofthe spring bears against a, spring support I3! which is secured to theupper end of the valve stem I29. The auxiliary air tank III is securedto the underside of the valve housing II9 by means of a plurality ofbolts I39 (only one being shown) which extend through the valve housingi it and engage an annular flange MI formed on the. neck of the air tankIII, thereby clamping the flange tightly against the underside of thevalve housing H9. A sealing ring 543 is inter posed between the valvehousing and the flange MI of the auxiliary air tank iII to tightly sealthe joint there-between. The auxiliary air tank i H is connected to amain air storage tank (not shown) by moans of a conduit M5, compressedair being supplied to and maintained in the main storage tank by asuitable motor driven compressor unit, not shown.

The main inlet valve I21 is adapted to be opened by means of a valvepiston I4! to admit compressed air into the upper end of the operatingcylinder 2% to close or automatically reclose the circuit breaker. Thevalve piston I4! is movable in a valve cylinder M9 formed in the valvehousing H9, and the valve piston is biased upwardly to an. inoperativeposition against the head of the valve cylinder by means of a helicalcompression spring I5I which surrounds a portion of a valve biasingpring and is disposed between the underside of the valve piston and ashoulder formed in the valve housing I IS.

The valve operating piston M1 is adapted to be moved downwardly to openthe main inlet valve, by compressed air from the auxiliary air tank Ill,through passages I52 and E53 formed in the valve housing II 9, the valvepiston I l! being suitably recessed at its upper end, as shown in Fig.1, for the purpose of permitting the compressed air to move the pistondownwardly from its upper inoperative. position. The air passages andI53 communicate with cooperating passages in the pilot valve housin I55which is secured to the main valve housing H9. Communication between.the auxiliary air tank and the upper end of the valve cylinder I isnormally shut ofi, however, by a pilot valve I51 disposed in the pilotvalve housing 555. The pilot valve I5! is biased to closed positionagainst its seat by a compression spring I59 which bears against theunderside of the pilot valve. The pilot valve is adapted to be operatedto open position to cause air pressure to open the main inlet valve, bymeans of the electromagnet I I! upon energization thereof.

The cylinder portion I49 of the main inlet valve housing is providedwith a plurality of ports lid (only one being shown) adjacent the lowerend of the cylinder 549 which open to the atmosphere. These portsfunction to prevent the main inlet valve from being reclosed by thedifferential pressure on the under side of the valve piston I41 aided bythe force of the springs I35 and I5!, as the main inlet valve 22.!opens. A skirt on the lower end of the valve piston M! closes the portsI555 as the piston I4! reaches the bottom end of its stroke to preventany further leakage of the closing air pressure through ports 59. Theports E also function to slowly exhaust the air pressure in theoperating cylinder 23 after the completion of a normal closingoperation.

The electromagnet II! comprises a frame I6! and a core I53 both ofmagnetic material, an

energizing winding I65, and a pivoted armature I51. The electromagnet issecured to the pilot valve housing I55 by the lower end of the core I63being threaded into an opening in the upper end of the ilot valvehousing I55, thus clamping the winding spool and the frame IISI to thepilot Valve housing I55, the upper end of the core I63 having a shoulderwhich bears against a plate I59 which rests on the upper end of thewinding spool. The armature I51 of the electromagnet is pivotallysupported on the upper end of the frame IBI, and this armature engages aplunger I1I which extends slidably through an opening in the center ofthe core I33, and the plunger is connected at its lower end to the pilotvalve I51. The pilot valve biasing spring I59 normally maintains thepilot valve in closed position and the armature I61 in unattractedposition. A casing I13 is secured to the plate I59 and frame I6I, andthis casing encloses the armature I61.

When the electromagnet H1 is energized, the armature I61 thereof ismoved to attracted position depressing the plunger Ill and therebycausing opening of the pilot valve I51 to admit compressed air from theair tank II I to the upper end of the valve cylinder I49. The compressedair flowing into the upper end of the valve cylinder through thepassages I52 and I53 forces the valve piston I41 downwardly, therebycausing opening of the main inlet valve I21 to admit compressed air tothe upper end of the breaker operating cylinder 29. When the main inletvalve I21 is open, compressed air flows from the auxiliary air tank III,through the passages I2I and I23 into the main operating cylinder 29 andquickly moves the operating piston I93 downwardly to closed position,thereby closing the circuit breaker 1. As soon as the electromagnet II1is deenergized, the pilot valve I 51 immediately closes and the maininlet valve I21 is quickly returned by its biasing spring I35 to closedposition, the valve operating piston I41 being also returned upwardly toits upper inoperative position by the spring I5I.

A push button I extends through the casing I13 of the electromagnet andengages the armature I61. The push button I15 serves as a means formanually opening the pilot valve I51 to cause a closing operation of thecircuit breaker. The electromagnet I I1 of the pilot valve I I5 isadapted to be operated electrically to cause closing or automaticreclosing of the circuit breaker by circuit means which will behereinafter described.

In order to provide for quick reversal of move ment of the operatingpiston I93 and circuit breaker 1 (Fig. 3) to provide the effect of tripfree operation of the circuit breaker and to also provide for quickreclosing of the breaker, the operating cylinder 29 is provided with anair pressure exhaust means for causing quick collapse of air pressure inthe cylinder 29 whenever the tripping device BI is operated, the exhaustpassage of the exhaust means being so located that it is closed by themain operating piston before the piston reaches a position at whichcompressed air is admitted for quick reclosure. The pressure exhaustmeans comprises exhaust ports I8I formed in the side wall of theoperating cylinder, indicated by the dotted lines of Fig. 1.

Referring to Fig. 2, the exhaust ports I8I in the side of the mainoperating cylinder 29 communicate withv an exhaust passage I83 formed inthe valve housing I35 of a main exhaust valve indicated generally at I81(Fig. 2), The main exhaust valve housing I85 is secured to the side ofthe operating cylinder 29 by a plurality of bolts (not shown), and theexhaust passage I83 extends through the valve housing and is open to theatmosphere at a port I88 on one side of the valve housing I85. Theexhaust passage I83, however, is normally closed by a piston typeexhaust valve I39 which is slidably mounted in a cylinder I9I formed inthe exhaust valve housing I85. The piston type exhaust valve I89 isbiased upwardly to closed position in which it closes the exhaustpassage I83, by means of a helical compression spring I93 disposedwithin the valve cylinder. The upper end of the biasing spring I93 bearsagainst the underside of the top of the piston valve I89 and the lowerend of the spring bears against the bottom closure plate I55 01 thevalve cylinder I9I, An annular guide projection I91 is formed integralwith the bottom end plate I95 of the valve cylinder I9I and acooperating cylindrical shaped projection I99 is formed on the inside ofthe piston I89. The projections I91 and 199 serve as a guide for thebiasing spring I93, and when the exhaust valve is moved downwardly toopen position, the cylindrical projection I99 slides into the annularprojection I31 to provide a cushioning effect by the trapped air in thebottom of the annular projection I31 at the end of the opening movementof the exhaust valve I89. The exhaust ports I8I and exhaust passage I83are of a size sufficient when the exhaust valve is open to cause quickcollapse of air pressure in the main operating cylinder 29 even thoughthe main inlet valve I21 may be open. The exhaust passage and exhaustvalve operate to quickly dump the air pressure in the main operatingcylinder 29 whenever the trip device BI is operated, thus preventing anyair pressure on the closing side of the main operating piston Hi3 fromretarding opening movement of the circuit breaker when the circuitbreaker is called upon to open. Opening of the main exhaust valve IE9 iscontrolled by a pilot valve, indicated generally at ZBI, which isadapted to be operated by the trip device 8I, Actual opening movement ofthe main exhaust valve I89 is produced by air pressure from the mainoperating cylinder 29, when the pilot valve is opened by the operationof the trip device 8|.

The exhaust pilot valve comprises a light pilot valve element 293movable in an opening 294 provided therefor in the pilot valve housing205 which is formed integral with the main operating cylinder casting21. If desired the pilot valve housing 295 may be made as a separatecasting secured to the cylinder 29. The pilot valve element 293 isdirectly mechanically connected to the lower end of the trip plunger 19which is connected to and extends through the armature B1 of the tripdevice. An air passage 291 formed in the cylinder casting 21communicates with the main operating cylinder at one end and at theother end with the valve opening 204, in which the pilot valve element293 slides, The valve opening 294 is in communication with a passage.

2II (Fig. 2) formed in a closure plate 2I2 which is secured to thebottom of the pilot valve housing 295. A conduit 2I3 (Fig, 2) connectsthe air passage 2II to a recess 2I5 in the upper end of the exhaustvalve cylinder I9l above the piston type main exhaust valve I89. The topof the main exhaust valve I89 is recessed, as shown in Fig. 2, to permitthe air pressure admitted through the conduit 2I3 when the pilot valveis opened, to initiate opening movement of the main exhaust valve I89.As soon as the main exhaust valve I89 is opened a small distance by airpressure through the conduit 2I3, the air pressure flowing from the mainoperating cylinder 29, through the exhaust passage I83 passes over thetop of the main exhaust valve I89 and the pressure quickly forces themain exhaust valve downwardly to open position and maintains it in openposition against the force of the main exhaust valve spring I93 untilthe pressure in the main operating cylinder 29 has collapsed to apredetermined value whereupon the spring I93 immediately recloses themain exhaust valve. The air trapped in the annular projection I9'I bythe piston type projection I99 assists the spring I93 in quicklyreturning the main exhaust valve to closed position upon collapse ofpressure in the breaker operating cylinder. The biasing spring 39 of thetrip plunger 19 serves to return the exhaust pilot valve 293 to closedposition as soon as the trip device BI is deenergized.

A port H9 is provided in the lower end of the exhaust valve cylinder I9Ito permit opening of the piston type main exhaust valve I89, the port2I9 being opened to the atmosphere to allow air beneath the piston I99to escape upon downward movement of the piston of the valve One or moresmall bleeder openings 22I are provided in the top of the piston typemain exhaust valve I89 to prevent leakage air from the pilot valve 29Iand from the main cylinder 29 from falsely operating the exhaust valveI89.

The exhaust ports I8! are located in the side wall of the cylinder 29 ata point intermediate the end positions of the operating piston H33 sothat these exhaust ports will be closed by the main operating piston I03after the breaker has opened a predetermined distance sufiicient tointerrupt the circuit and before the main operating piston reaches theposition at which compressed air is admitted for quick automaticreclosing of the breaker. This arrangement prevents the dumping of thequick reclosing air pressure and also allows a time interval for themechanical closing of the main exhaust valve 99 on a quick reclosingoperation of the mechanism. The closing of the exhaust ports I8I by thepiston I93 also acts to provide a cushioning action for the partialopening stroke of the breaker and piston during a quick reclosingoperation. It

will thus be seen that the pressure exhaust means in addition toproviding trip free action to permit quick reversal of switchingmovement during closing or reclosing and substantially unretardedopening movement of the breaker, also provides for quick reversal of theopening movement during a quick reclosing operation by preventing thedumping of the reclosing air during the initial portion of the reclosingoperation, before the exhaust valve I91 closes.

A pair of auxiliary switch devices 225 and 22'! is mounted on a bracket229 secured to the main casting 27. Each of these auxiliary switchdevices comprises a multi-pole auxiliary switch of conventionalconstruction, wherein the individual switch poles are adjustablerelative to their operating shafts 23I and 233, respectively, where bythe auxiliary switches may be set to operate at predetermined desiredpoints in the operation of the main circuit breaker I. The operatingshaft 23! of the auxiliary switch device 225 is connected by a crank 235and link 231 to the projection 239 of an auxiliary switch operatinglever MI. The lever 24I is pivotally mounted on the fixed pivot pin 53and the free end of this lever is connected by a slot 249 to the pivotpin 49 which connects the circuit breaker operating rod 25 to theoperating lever 55. The operating shaft 233 of the auxiliary switchdevice is also connected by a crank 245 and a link 25? to the projection 239 of the auxiliary switch operating lever 2 Thus each of theauxiliary switch devices 225 and 22? is operated by and in accordancewith the movement of the circuit breaker '5'.

Referring now to Fig 3 which diagrammatically shows the circuits forelectrically controlling the inlet valve electromagnet II? and the tripdevice 8!. 25I and 253 designate a pair of supply conductors connectedto a source of electric energy (not shown). The winding I65 of theelectromagnet Ill which controls the admission of compressed air to theoperating cylinder for closing the circuit breaker, is connected in anenergizing circuit 255 extending from the supply conductor 25I, throughthe Winding I55, through back contacts 251 of a release relay 259 andfront contacts 26! of an operating relay 293 to the supply conductor253. The energizing winding of the operating relay 263 is connected inan energizing circuit which extends from the supply conductor 253,through a conductor 295, back contacts 26'! of the release relay 259,energizing winding of the operating relay 259, conductor 259 and througha manual control switch 2' for controlling normal closing operation ofthe circuit breaker, to the supply conductor 25L The energizing windingof the release relay 259 is connected in an energizing circuit whichextends from the supply conductor 253, through an auxiliary switch 213which is adapted to be closed when the circuit breaker reaches closedposition, through a conductor 215, energizing winding of the releaserelay 259, conductor 21?. through the front contacts 2'58 of theoperating relay 253 and through a conductor 219 to the supply conductor25I.

A stick circuit is provided for maintaining the operating relay 253energized after a momentary operation of the manual closing controlswitch 2. This stick circuit extends from the supply conductor 253,through the conductor 255 and back contacts 267 of the release relay259, energiZing winding of the operating relay 253, and through aconductor 283, conductor 27?, front contacts 218 of the operating relayand conductor 279 to the supply conductor 25!. A locking circuit is alsoprovided for maintaining the release relay 259 energized until themanual closing control switch 2' has been opened. This locking circuitfor the relay 259 extends from the supply conductor 253, through aportion of the conductor 265, front contacts 285 of the release relay259, energizing winding of release relay 259, conductor 283, conductor299 and the manual closing control switch 2' to the supply conductor 25I.

The winding of the trip device BI is connected in an energizing circuitwhich extends from the supply conductor 253, through conductor 287,through an auxiliary switch 299 which is closed when the circuit breakeris closed, conductor 29I, energizing winding of the trip device 8i,conductor 293 and the contacts 295 of a fault responsive relay 29? andthrough a conductor 299 to the opposite supply conductor 25L The faultresponsive relay 291 is arranged to be operated to close its contacts295 upon the occurrence of a predetermined overload, such, for example,as a short circuit in the main circuit I3 controlled by the circuitbreaker I. For this purpose, the energizing winding of the protectiverelay 291 is arranged to be energized by a current transformer 39!associated with the main circuit conductor !3. Thus when a predeterminedoverload condition or short circuit ocours in the main circuit !3controlled by the breaker I, the fault responsive relay 291 becomesenergized a suflicient amount to close its contacts, thereby effectingenergization of the trip device 8!. When the trip device 8! isenergized, it causes release of the latching means 5!, 1! and circuitbreaker operating lever 35, whereupon the circuit breaker is quicklymoved to open position by its biasing springs.

The circuit breaker 1 may also be tripped open manually by means of amanually operable trip control switch 303 connected in series with aconductor 395 which is arranged to shunt the contacts 295 of theprotective relay 291.

The circuit breaker 1 is adapted to be automatically reclosedimmediately following interruption of the circuit by the circuit breaker1, through the agency of a reclosing relay 391. Automatic reclosingmovement of the circuit breaker is preferably initiated immediatelyafter the circuit breaker has interrupted the circuit and before thecircuit breaker reaches full open position. Reclosing relay 391 has itscontacts 309 connected in series with a conductor 3!! which is connectedin shunt relation to the contacts f the manual closing control switch21!. A manually operable switch 3i3 is provided in the conductor 3!! forthe purpose of preventing quick automatic reclosing operation of thecircuit breaker if automatic reclosing is not desired. The energizingwinding of th reclosing relay 301 is connected in series in anenergizing circuit 3!5 which extends from the supply conductor 253,through the winding of the reclosing relay 301, through an adjustableauxiliary switch 3l1 which is adjusted to close during the initialopening movement of the circuit breaker, and through contacts 3!9 of theprotective relay 291 and conductor 299 to the opposite supply conductor25!.

The operation of the mechanism is as follows, assuming the circuitbreaker to be in closed position, as shown in Figs. 1 and 3. When apredetermined overload or short circuit occurs in the main circuit !3controlled by the circuit breaker 1, the fault responsive relay 291 isimmediately energized and closes its contacts 295 to efiect energizationof the trip device 8 I. When the trip device 8! is thus energized, itmoves the trip plunger 19 upwardly to cause the auxiliary latch 61 torelease the main latch thereby releasing the breaker operating lever 35.The circuit breaker is immediately moved to open position by its biasingspring !5. The operation of the trip plunger 19 also opens the pilotvalve 293, thereby causing the main exhaust valve to be opened andquickly exhaust any air pressure in the operating cylinder 29, if thereis any pressure in the cylinder 29 at this time. The main circuit I3 isinterrupted during the first part of the opening movement of the circuitbreaker 1 by the time the circuit breaker has opened through only a partof its full open distance.

Assuming the manual switch 3l3 to be closed, quick automatic reclosingoperation of the circuit breaker will be caused to take place as soon asthe circuit breaker has opened through a predetermined distance, lessthan the full open distance, Quick automatic reclosing operation of thecircuit is accomplished by the reclosing relay 301 in response toclosing of its circuit by the contacts 3l9 of the fault responsive relay291 and closing the adjustable auxiliary switch 3l1. The contacts 3!9 ofthe fault responsive relay are closed simultaneously with the contacts295 upon operation of the fault responsive relay in response to anoverload or short circuit, thus immediately preparing the energizingcircuit for the reclosing relay 391. During the initial opening movementof the circuit breaker, the aux--v iliary switch 3!1 closes andcompletes the energizing circuit for the reclosing relay 391', and therelay 391 thereupon closes its contacts 399, completing an energizingcircuit for the operating relay 263, this energizing circuit extendingfrom the supply conductor 25!, through the contacts 399 of the reclosingrelay, conductor 3!!, conductor 269, energizing winding of operatingrelay 263, back contacts 261 of the release relay 259, and conductor 265to the opposite supply conductor 253. The operating relay instantlycloses its contacts 218 and 23!. Closing of the operating relay contacts26! completes an nergizing circuit for the inlet valve controllingelectromagnet l!1, through the back contacts 251 of the release relay,and through conductor 255. The electromagnet I !1 when energized opensthe pilot valve !51, thereby causing opening of the main inlet valve!21. Compressed air is thereupon admitted to the upper end of theoperating cylinder 29 quickly moving the operating piston ma downwardlyto close the circuit breaker. These operations occur substantiallyinstantaneously so that reclosing movement of the operating piston isinitiated immediately after the circuit has been interrupted and beforethe breaker reaches the full open position. The position at whichautomatic reclosing movement of the main operating piston I93 takesplace is indicated by the dotted lines R in Fig. 1. As has previouslybeen explained, the exhaust ports !8! are located in a position suchthat they are closed by the operating piston I03 during the first partof the opening movement of the breaker before the piston reaches theposition at which compressed air is admitted for quick reclosure, sothat dumping of the reclosing air is thereby prevented and the exhaustvalve [89 is given a time interval to mechanically close before thedownward movement of the operating piston opens the exhaust ports !8!.

Closing of the contacts 218 of the operating relay 263 prepares anenergizing circuit for the release relay 259. This circuit extendingfrom the supply conductor 25!, through conductor 219, contacts 218,conductor 211, energizing winding of the release relay 259, conductor215 to the auxiliary switch 213 which closes the instant the circuitbreaker reaches closed position. As soon as the circuit breaker reachesclosed position, the auxiliary switch 213 completes the energizingcircuit for the release relay 259, whereupon the release relay operatesto open its back contacts 261 and 251 and closes its front contacts 285.The opening of contacts 251 effects deenergization of the inlet valvecontrolling electromagnet !!1, thereby causing shutting off the supplyof compressed air to the operating cylinder 29, and the opening ofcontacts 231 efiects deenergization of the operating relay 263. Theclosing of the front contacts 285 normally produces no effect duringquick automatic reclosing operation, since the contacts 399 of thereclosing relay open before the breaker reaches closed position.

If the condition which caused the overload or short circuit has beenremoved by the time the circuit breaker completes the circuit upon aquick automatic reclosing operation, the circuit breaker remains closedand the control circuits assume the normal condition shown in Fig. 3.However, if the fault condition which causes the overload or shortcircuit is still present at the time the circuit is completed by thecontacts of the circuit breaker during a quick reclosing operationthereof, the fault responsive relay 23! is again energized the instantthe main circuit is completed again causing energization of the tripdevice 8!. Consequently trip plunger 19 is again operated. upwardlyopening the pilot valve 203, thereby causing the air pressure in theoperating cylinder 29 to open the main exhaust valve I89 and quicklycause collapse of the air pressure in the operating cylinder 29 eventhough the main inlet valve !2'! may still be open at this time. Thetrip device 8| also moves the latches to released position. Thus thecircuit breaker is caused to quickly reverse its movement and startopening even though the inlet valve may be open at this time. Theopening movement of the circuit breaker is substantially unretarded dueto the quick collapse of air pressure in the operating cylinder 29. Alockout device 32! of any conventional construction may be provided inthe circuit of the reclosing relay 3!]? to prevent more than one quickautomatic reclosing operation of the circuit breaker, or to open thequick reclosing circuit and transfer control of the reclosing relay to atime delayed reclosing device in a manner well known in the art. If thelockout device 32! is of a character to provide for only a single quickautomatic reclosure of the circuit breaker, the circuit breaker proceedsto the full open position and remains open after one unsuccessfulattempt at quick reclosure.

Normal closing operation of the circuit breaker from the full openposition is accomplished by closing the manual control switch 21!. Theclosing of this switch completes an energizing circuit for the operatingrelay 263. When the operating relay is thus energized, it closes itscontacts 26! and 218, the closing of contacts 26! completing anenergizing circuit for the inlet valve controlling electromagnet H1,thereby causing compressed air to be admitted to the operating cylinderto close the circuit breaker. The contacts 218 prepare an energizingcircuit for the release relay 259, this circuit being completed by theauxiliary switch 213 when the breaker reaches the fully closed position.The manual closing control switch 21! need only be closed for an instantbecause as soon as the operating relay closes its contacts 218, a stickcircuit is completed for maintaining the operating relay energized untilthe release relay operates. This stick circuit has been previouslydescribed. Closing of the contacts 218 of the operating relay 263prepares an energizing circuit for the release relay 259 which iscompleted by the auxiliary switch 213 when the breaker reaches the fullyclosed position. When the release relay 259 is energized, it opens itsback contacts 25! and 261, thereby deenergizing the inlet valvecontrolling electromagnet I !'l by the contacts 25! and alsodeenergizing the operating relay 263 by the contacts 26! nd .preventingfurther energization of the operating relay as long as these contactsremain open. The operation of the release relay also closes its frontcontacts 285 to complete a locking circuit for maintaining the releaserelay energized as long as the manual closing control switch 21! is heldclosed, this locking circuit extending from the supply conductor 253,through the front contacts 285 and energizing winding of the releaserelay 259, conductor 283, conductor 269 and manual closing controlswitch 21! to the supply conductor 25 I. This locking circuit thusprevents the circuit breaker from pumping if the breaker will not remainclosed and the manual control switch is held in closed position. If thecircuit breaker should be closed against an overload or short circuitduring a normal closing operation, the trip device 8! will be operatedto release the latch and cause opening of the exhaust valve !81 so thatthe breaker will immediately open even though the inlet valve I89 may beopened at the time the circuit is completed.

The circuit breaker may be manually tripped open by closing the manualtrip control switch 303 which effects energization of the trip device 8!and tripping of the circuit breaker.

A modification of the main exhaust valve is illustrated in Fig. a. Theconstruction of thi modified form of the exhaust valve is substantiallythe same as that shown in the original embodiment, except that the valvecylinder is open at its lower end and the lower end of the valve biasingspring is mechanically connected to the auxiliary switch operating lever24%. Referring to Fig. 4, the modified exhaust valve comprises a valvehousing 325 secured to the side of the main operating cylinder 29. Thevalve housing is formed to provide a valve cylinder 32? which is open atit lower end, and the housing contains the exhaust passage 329 which isopen to the atmosphere at one end and communicates at its other end withthe exhaust ports Hit of the operating cylinder 29. The exhaust valve33! is a piston type valve which i slidably mounted in the valvecylinder 32?. The valve 33! is biased upwardly to closed position toclose the exhaust passage 329 by means of a helical biasing spring theupper end of which bears against the underside of the piston typeexhaust valve. The lower end of the spring 333 bears against a springsupport 335 which is carried by a connecting rod 33?. The connecting rod331 slidably extends through openings provided in the valve 33! andvalve housing 325, and the upper end of the connecting rod is pivotallyconnected at 338 to the auxiliary switch operating lever 26!. The upperend of the valve cylinder 32'! has a passage 2I5 which is connected byconduit 2!? to the pilot valve passage 2! l in the same manner as shownand described in connection with the original embodiment, and the upperend of the piston type valve 33! is provided with a recess so thatcompressed air admitted through the conduit 2!3 to the upper end of thecylinder can initiate opening of the exhaust valve 33!. The purpose ofconnecting the lower end of the valve biasing spring to the auxiliaryswitch operating lever 24! is to provide for additional compression ofthe spring as the circuit breaker operating mechanism opens in order toinsure quick closing of the exhaust valve and to prevent the valve fromsticking open after the air in the breaker operating cylinder has beenexhausted. The remaining structure of the exhaust valve and its functionis substantially the same as in the case of the original embodiment.

While the invention has been disclosed in accordance with the provisionof th patent statutes, it is to be understood that various changes inthe structural details and arrangements of parts thereof may be madewithout departing from some of the essential features of the invention.

We claim as our invention:

1. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonin said cylinder operatively related to the breaker, a source ofcompressed air for operating said piston to close the breaker, meansincluding an inlet valve operable to connect said source of compressedair to said cylinder to close the breaker, latching means for releasablyholding said breaker closed, trippin means operable in response topredetermined abnormal conditions in the circuit to cause said latchingmeans to release the breaker and thereby cause opening of the breaker,air pressure exhaust means connected to said cylinder intermediate itsends so as to be closed off by said piston when in an intermediateposition, said exhaust mean including a normally closed exhaust valvedirectly connected to said cylinder apart from the connection to saidsource of compressed. air, said valve when opened causing quick collapseof pressure in said cylinder except when said piston is at or to oneside of said intermediate position, and means operated by said trippingmeans upon operation thereof for causing opening of said exhaust valve.

2. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonin said cylinder operatively related to the breaker, a source ofcompressed air for operating said piston to close the breaker, meansincluding an inlet valve operable to connect said source of compressedair to said cylinder to close the breaker, latching means for releasablyholding said breaker closed, a tripping electromagnet having an armatureoperable upon the occurrence of predetermined abnormal conditions in thecircuit to cause said latching means to release said breaker and therebycaus opening of the breaker, air pressure exhaust means associated withsaid operating cylinder including an exhaust valve biased closed andhaving a piston Operable by air pressure to open said valve, saidexhaust valve when opened causing quick collapse of pressure in saidbreaker operating cylinder, and means including a normally closed pilotvalve operable by the armature of said tripping electromagnet uponoperation thereof to cause opening of said exhaust valve.

3. An operating mechanism for a circuit breaker comprising an operatingcylinder, a piston reciprocable in said cylinder for actuating thebreaker, a source of compressed air for operating said piston, an inletvalve operable to connect one end of said cylinder to said source ofcompressed air to close the breaker, means operable to cause opening ofthe breaker, an electromagnet having an armature operable in response tothe occurrence of predetermined abnormal conditions to cause operationof said means to open the breaker, air pressure exhaust means associatedwith said operating cylinder including an exhaust valve biased closedand having a piston operable by air pressure to open said exhaust valve,said exhaust mean when said exhaust valve is open causing quick collapseof air pressure in said cylinder on the closing side of said breakeroperating piston when said breaker-operating piston is in or adjacentclosed position, and a normally closed pilot valve operable by thearmature of said electromagnet upon operation thereof to cause openingof said exhaust valve.

4. An operating mechanism for a circuit breaker comprising an operatingcylinder, at piston reciprocable in said cylinder for actuating thebreaker, a source of compressed air for operating said piston, an inletvalve operable to connect one end of said cylinder to said source ofcompressed air to close the breaker, means operable to cause opening ofthe breaker, an electromagnet having an armature operable in response tothe occurrence of predetermined abnormal conditions to cause operationof said means to open the breaker, an air pressure exhaust passagecommunicating with said operating cylinder of a size to cause quickcollapse of pressure in said operating cylinder on the closing side ofsaid piston even though said inlet valve is open, a piston type exhaustvalve in said passage biased to normally close said passage, saidexhaust valve being operable to open position to open said passage whenair pressure is applied to one end of the piston of said valve, anauxiliary air passage connecting a portion of said operating cylinderwith said one end of said piston valve, a pilot valve in said auxiliarypassage biased to close said passage, said pilot valve being connectedto the armature of said electromagnet to be opened thereby when saidarmature is operated to thereby cause opening of said exhaust valve byair pressure in said cylinder.

5. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonin said cylinder connected to the breaker, a source of compressed airfor operating said piston to close the breaker, means including an inletvalve operable to connect said source of compressed air to said cylinderto close the breaker, latching means for releasably holding said breakerclosed, a tripping electromagnet having an armature operable upon theoccurrence of predetermined abnormal conditions in the circuit to causesaid latching means'to release the breaker and thereby cause opening ofthe breaker, a pressure exhaust passage communieating with said cylinderof a size to cause quick collapse of pressure in said cylinder when saidpassage is open, a piston type exhaust valve in said passage normallybiased closed to close said passage, said exhaust valve being operableto open position when a predetermined air pressure is applied to one endof the piston of said valve, an auxiliary air passage connecting aportion of said cylinder with the exhaust valve housing adjacent saidone end of the valve piston, a pilot valve in said auxiliary passagebiased to normally close said passage, said pilot valve being connectedto the armature of said tripping electromagnet to be opened thereby whensaid armature is operated to thereby cause opening of said exhaust valveby air pressure in said cylinder.

6. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising compressed air operated closingmeans for closing the breaker, latching means for releasably holdingsaid breaker in closed circuit position, tripping means operable inresponse to predetermined abnormal conditions in the circuit to causesaid latching means to release the breaker and thereby cause opening ofthe breaker, means automatically operable to initiate an instantaneousreclosing operation of the closing means after interruption of thecircuit and at least by the time the breaker reaches full open position,air pressure exhaust means associated with said closing means includinga normally closed exhaust valve operable to cause a quick collapse ofclosing air pressure in said closing means, said tripping means whenoperated causing opening of said exhaust valve, and means responsive tothe position of said closing means for mechanically closing said exhaustmeans when said closing means is in the neighborhood of its openposition.

7. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonin said cylinder operatively related to said breaker, a source ofcompressed air, an inlet valve operable to connect said source of compressed air to one end of said cylinder to effect closing of thebreaker, latching means for releasably holding said breaker closed,tripping means operable upon the occurrence of predetermined overloadconditions in the circuit to cause said latching means to release thebreaker and thereby cause opening of the breaker, means operable toautomatically open said inlet valve to cause said operating piston toinitiate reclosing of the breaker after interruption of the circuit andbefore said breaker reaches the full open position, an air pressureexhaust passage communicating with said cylinder at a point intermediateits ends, said exhaust passage being of a size sufiicient to cause quickcollapse of pressure in said cylinder even if said inlet valve is openwhen the piston is near the end of its stroke opposite the inlet end ofthe cylinder and said exhaust passage being closed off from the inletwhen the piston is between said intermediate point and the inlet end ofthe cylinder sov as to permit quick reclosing of the breaker beforereaching full open position, an exhaust valve in said passage biased tonormally close said exhaust passage, and means operated by said trippingmeans upon operation thereof to cause opening of said exhaust valve.

8. In combination, a circuit breaker biased to open circuit positionoperating mechanism therefor comprising an operating cylinder, a pistonmovable in said cylinder and operatively related to said breaker, asource of compressed air, means including an inlet valve for connectingone end of said cylinder to said source of compressed-air to effectclosing of the breaker, latching means for releasably holding saidbreaker closed, tripping means operable upon the occurrence ofpredetermined overload conditions in the circuit to cause said latchingmeans to release the breaker and thereby cause opening of the breaker, apressure exhaust passage communicating with said cylinder through theside Wall of the cylinder at a predetermined point intermediate the endpositions of said piston, said passage having a size such as to cause aquick collapse of pressure in said cylinder when said passage is openeven if said inlet valve is open, an exhaust valve in said passagenormally biased closed to close said exhaust passage, and means operatedby said tripping means upon operation thereof for causing opening ofsaid exhaust valve.

9. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonmovable in said cylinder and operatively related to said breaker, asource of compressed air, means including an inlet valve for connectingone end of said cylinder to said source of compressed air to effectclosing of the breaker, latching means for releasably holding saidbreaker closed, tripping means operable upon the occurrence ofpredetermined overload conditions in the circuit to cause said latchingmeans to release the breaker and thereby cause opening of the breaker, apressure exhaust passage communieating with said cylinder of a sizesufficient to cause quick collapse of pressure in said cylinder whensaid passage is open even if said inlet valve is open, an exhaust valvein said passage biased to normally close said passage, means operatedsubstantially simultaneously with said tripping means for causingopening of said exhaust valve, said exhaust passage being closed by apart movable in accordance with the movement of said piston when saidpiston is within a predetermined distance of the full open position.

10. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, a pistonmovable in said cylinder and operatively related to said breaker, asource of compressed air, means including an inlet valve for connectingone end of said cylinder to said source of compressed air to effectclosing of the breaker, latching means for releasably holding saidbreaker closed, tripping means operable upon the occurrence ofpredetermined overload conditions in the circuit to cause said latchingmeans to release the breaker and thereby cause opening of the breaker, apressure exhaust passage communicating with said cylinder through theside wall thereof at a point intermediate the ends thereof, said passagebeing of a size sufficient to cause quick collapse of pressure in saidcylinder when said passage is open, an exhaust valve in said passagenormally biased closed, means operated by said tripping means uponoperation thereof for causing opening Of said exhaust valve, saidoperating piston closing communication between a portion of saidcylinder and said exhaust passage when the breaker is opened more than apredetermined distance to permit quick reclosing operation of thebreaker and allow said exhaust valve to close during a quick reclosingoperation.

11. An operating mechanism for a circuit breaker comprising an operatingcylinder, a piston in said cylinder operatively related to the breaker,a source of compressed air for actuating said piston, means including aninlet valve operable to connect one end of said cylinder to said sourceof compressed air to effect closing of the breaker, latching means forreleasably holding the breaker closed, tripping means operable upon theoccurrence of predetermined overload conditions to cause said latchingmeans to release the breaker and thereby cause opening of the breaker, apressure exhaust passage communicating with said cylinder through theside Wall thereof, said passage being of a size sufficient when saidpassage is open to cause quick collapse of pressure in said cylindereven if said inlet valve is open, a piston type exhaust valve in saidpassage biased to normally close said passage, means operatedsubstantially simultaneously with said tripping means for causing saidexhaust valve to be opened by air pressure in said cylinder, saidoperating piston closing said exhaust passage off from a portion of thecylinder when said breaker has opened a predetermined amount less thanthe full opening distance.

12. An operating mechanism for a circuit breaker comprising an operatingcylinder, a piston in said cylinder operatively related to the breaker,a source of compressed air for actuating aroma;

said piston to close the breaker, means including an inlet valveoperable to connect one end of said cylinder to said source ofcompressed air to effect closing of the breaker, means operable to causeopening of the breaker, an electromagnet having an armature operableupon the occurrence of predetermined overload conditions in the circuitto cause operation of said means to open the breaker, a pressure exhaustpassage communicating with said cylinder, said passage being of a sizesufficient when said passage is open to cause quick collapse of pressurein said cylinder even if said inlet valve is open, a piston type exhaustvalve in said passage, spring means for biasing said exhaust valve tonormally close said passage, means operated by the armature of saidelectromagnet upon operation thereof to cause said exhaust valve to beopened by air pressure in said cylinder, and a connection between saidspring means and a part movable with said piston for moving said springto increase the force acting to close said exhaust valve during openingof the breaker.

13. Operating mechanism for a circuit breaker comprising an operatingcylinder, a piston in said cylinder operatively related to the breaker,a source of fluid under pressure for actuating said piston, meansincluding an inlet valve operable to connect one end of said cylinder tosaid source of fluid under pressure to effect closing of the breaker,means operable to cause opening of the breaker, an electromagnet havingan armature operable upon the occurrence of predetermined overloadconditions in the circuit to cause operation of said means to open thebreaker, means automatically operable to open said inlet valve toinitiate quick automatic reclosing operation of the breaker afterinterruption of the circuit but before the breaker reaches full openposition, a fluid pressure exhaust passage communicating with saidcylinder at a point intermediate the end positions of said piston, saidpassage being of a size suflicient when said passage is open to causequick collapse of fluid pressure in said cylinder on the closing side ofthe piston even if said inlet valve is open, a piston type exhaust valvein said passage, spring means biasing said exhaust valve closed tonormally close said exhaust passage, means operated simultaneously withthe operation of said armature to cause said exhaust valve to be openedby fluid pressure in a portion of said cylinder, said breaker operatingpiston closing off communication between said exhaust passage and aportion of the operating cylinder after said breaker has opened a Ypredetermined amount but before the time at which fluid under pressureis admitted to said cylinder for a quick automatic reclosing operation,thereby preventing dumping of the reclcsing fluid pressure in saidcylinder during the first portion of a quick reclosing operation andallowing a time interval for mechanical closing of said exhaust valve.

14. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor, comprising an operating cylinder, a pistonin said cylinder operatively related to the breaker, a source of fluidunder pressure for actuating said piston to close the breaker, meansincluding an inlet valve operable to connect one end of said cylinder tosaid source of fluid under pressure to effect closing of the breaker,latching means for holding said breaker closed, tripping means operableupon the occurrence of predetermined overload conditions in the circuitto cause said latching means to release the breaker and thereby causeopening of the breaker, means automatically operable to open said inletvalve to initiate a quick automatic reclosing operation of the breakerafter interruption of the circuit but before said breaker reaches fullopen position, a fluid pressure exhaust passage communieating with saidcylinder at a point intermediate the end positions of said piston, saidpassage being of a size sufficient when said passage is open to causequick collapse of fluid pressure in said cylinder even if said inletvalve is open, a piston type exhaust valve in said passage biased by aspring to normally close said passage, means operated by said trippingmeans upon operation thereof for causing said exhaust valve to be openedby fluid pressure in a portion of said cylinder, said breaker operatingpiston acting to close off communication between said exhaust passageand a portion of the operating cylinder after said breaker has opened apredetermined amount but before the time at which fluid under pressureis admitted to said cylinder for a quick automatic reclosing operation,thereby preventing dumping of the reclosing fluid pressure in saidcylinder during the first portion of a quick reclosing operation andallowing a time interval for mechanical closing of said exhaust valve.

15. In combination, a circuit breaker biased to open circuit position,operating mechanism therefor comprising an operating cylinder, 2. pistonin said cylinder operatively related to the breaker, a source ofcompressed air for operating said piston to close the breaker, meansincluding an inlet valve operable to connect said source of compressedair to said cylinder to close the breaker, latching means for releasablyholding said breaker closed, electromagnetic tripping means operable inresponse to predetermined abnormal conditions in the circuit to causesaid latching means to release the breaker to thereby cause opening ofthe breaker, exhaust means associated with said cylinder includin apiston type exhaust valve biased closed and operable by air pressure tocause a quick collapse of pressure in said operating cylinder even ifsaid inlet valve is open, means including a normally closed pilot valveoperable to cause opening of said exhaust valve, and means for causingopening of said pilot valve substantially simultaneously with theoperation of said electromagnetic tripping means. i

16. In combination, a circuit breaker, operating mechanism thereforcomprising an operating cylinder, a piston in said cylinder operativelyrelated to the breaker, a source of compressed air for operating saidpiston, means including an inlet valve operable to connect said sourceof compressed air to said cylinder to close the breaker, latching meansfor holding said breaker in closed position, tripping means operable inresponse to predetermined abnormal conditions in the circuit to causesaid latching means to release the breaker, a, compressed air operateddump valve directly connected to said cylinder apart from the connectionto said pressure source for instantaneously reducing back pressureagainst said piston so that high speed opening operation of said breakermay be obtained and means for causing opening of said dump valve inresponse to operation of said tripping means by pressure air from thecylinder if, and only if, there is pressure air in the cylinder.

17. A pneumatic operating mechanism of the trip-free type for anelectric circuit breaker com- 21 prising a source of compressed gas, afluid motor including a piston and cylinder, an inlet to said cylinderfrom said source, a control valve between said source and inlet, saidvalve being arranged to admit gas under pressure from said source tosaid cylinder, means operatively relating said piston to said circuitbreaker for closing said breaker, a dump valve connected to saidcylinder intermediate its ends for venting rapidly said cylinder toatmosphere at the work ing face of said piston only when said piston ison the side of said dump valve connection opposite said inlet wherebysaid piston can then return toward its initial position notwithstandingflow of fluid under pressure from said source through said control valveand inlet to said cylinder, and means for causing opening movement ofsaid breaker and for also opening said dump valve for causing trip-freeoperation.

JAMES M. CUMMING. RICHARD C. CUNNINGHAM.

